Urban green and cold cash.

Sooner or later all whom tree huggers are challenged to place a dollar value on trees. In selfdefense, they may stutter back something like, "Trees are more than just amenities. They increase the value of real estate, cleanse they city's air and water, and reduce the energy used for heating and cooling."

Urban foresters have recently developed elaborate formulae for calculating property values, environmental values, energysaving values, and even psychological values of tress (see AMERICAN FORESTS, July/August 1988, September/October 1989). We have a good fix on the hard, tangible worth of trees-numbers, I should add, that help city foresters justify their budgets to the cold eyes of financial officers.

But in the rush of facts about the solid and impressive value of the city tree, we have begun to neglect its intangible, even spirtual, value-something we can all relate to on a personal level.

Over the past decade, researchers at the North Central Forest Experiment Station (U.S. Forest Service, 5801 N. Pulask Rd., Chicago, IL 60646) have diligently studied the ties between people and trees. In a recent paper titled "The Significance of Urban Trees and Forests-Toward a Deeper Understanding of Values," authors John Dwyer, Herbert Schroeder, and Paul Gobster outline the ddp psychological bonds between people and urban trees.

The authors point out that wilderness advocates have used psychological arguments for years to protect America's natural areas-hand have found strong support for preervation among urbanites. Similarly, urban forest advocates can use the city dweller's attraction to the natural environment to garner support for trees in cities. Urban natural areas, although not a spristine as remote wilderness, provide a daily contrast to and relief from brick, asphalt, and concrete-and urban nature is far more accessible. Just as efforts to preserve wilderness are often prompted by preceived threats to oldgrowth forest, efforts to preserve green space in cities is often inspired by the feeling that trees are threatened or vulnerable in the urban environment. Older trees that have survived represent an enduring element of nature deserving protection.

Light fillering through leaves and branches reveals ever-changing patterns of colore and texture, alternately revealing and hiding the surrounding urban environment. But the contribution of greenery goes deeper than simple beautification.

In a study of the visitors to Morton Arboretum in Lisle, Illinois, 80 percent praised green setting as "serene," "peaceful," and "restful." Studies by Roger Ulrich and his associates at Texas A & M University compared individuals viewing urban scenes with and without vegetation and measured the relaxation associated with views of greenery in terms of slower heartbeats, lower blood pressure, and more relaxed brain-wave patterns (AMERICAN FORESTS September/October 1989)

Individuals may react even more strongly to other sensory dimensions of the urban forest. Consider the fragrance of wet leaves in the fall or the sound of wind restling throught leaves or brances, so similar to the "white noise" used in hospital wards to mask disturbing sounds and help heartattack victims relax. Recordings of birds, wind, and rain in trees are marketed as aids for meditation.

As the Forest Service researchers point out, trees and forests reach out to the city dweller and convey serenity and beauty, surrounding us with dimensions of nature in an environment where nature is very scarce. Urban forests, and especially large trees or groups of trees, affect us in so many ways that the task of describing them is similar to that of describing what attracts us to a loved one, a home, or a profession.

To paraphrase the researchers, we can come up with lists of reasons but are seldom satisfied that we have captured them all-or the essence of the attraction.

The researchers add that many cultures have used tr ees to symbolize health and wisdom, and in a number of religious traditions, trees stand as a metaphorical link between the human and the divine. In our highly mobile society, tree planting is often taken as a symbol of stability or putting down roots. And with increasing recognition of globla environmental jproblems, tree planting is seen by many as one thing the individual can do to help.

With the support of Congress, President Bush, and local governments across the country-and with the help of researchers such as those at the North Central Forest Experiment Station-tree huggers need no longer stutter in their defense of trees.